#!/bin/bash

# version 1.0, 2003-08-01, Michael Wang <mwang@exchange.ml.com>.
# * emulate Solaris "ptree PID" command.
# * works under ksh (93), bash (2.05), and pdksh (v5.2.14).

shopt -s extglob 2>/dev/null

PID=$1
set --
flag=; unset flag
{ ps --forest -e -o pid,args
  printf "%s\n" "00000 a"
} | while IFS= read -r i; do
  if [[ $i == *( )+([0-9])@( )+([! ])* ]]; then
    if [[ $flag == Y ]]; then
      printf "%s\n" "$@"
      break
    else
      set -- "$i"
    fi
  else
    set -- "$@" "$i"
  fi
  [[ $i == *( )$PID+( )* ]] && flag=Y
done